1. Ceramic capacitors can use a variety of dielectrics, each of which has different characteristics, which can greatly affect performance within its temperature and voltage range. The two most common dielectrics are Y5V and X5R. Y5V dielectrics are inexpensive and can provide high capacitance in a small package, but their capacitance varies greatly within its voltage and temperature range and is not suitable for DC/DC applications.
X5R and X7R dielectrics are more suitable for output capacitor applications because their characteristics are more stable within their operating range and are highly recommended.
2. Correct selection of capacitor and inductor values will make the circuit more stable, but a good PCB design is still the key to avoiding high ripple or even self-oscillation.
3. By adding a PI filter, more ripple-sensitive power supplies of the MCU can be better protected (for example: analog voltage reference).
4. Keep enough power supply margin
The power supply must have sufficient margin, generally at least 20% more than the peak power consumption of the load, so that it is safer and will not cause unexpected failures.
When the power supply margin is insufficient, the power supply will work in the limit state, and the ripple of the power supply will rise sharply, reaching hundreds of mV or even a few V. Therefore, before determining the power input, it is best to estimate the maximum power consumption of the entire board subsystem.
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